She worked for Trump inside and outside the White House longer than any other senior administration official — going to work at the Trump Organization in 2014 and as the spokeswoman of his presidential campaign in 2015. Before that, she was a fashion model who came into Trump's orbit through work for his daughter Ivanka's fashion line.

White House press secretary Sarah Sanders said the resignation will take effect in the coming weeks or months. "There is no definitive timeline,” she said.

In the West Wing on Wednesday afternoon, applause could be heard in Sanders’ office as Hicks spoke to her staff about her departure.

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White House Communications Director Hope Hicks, one of President Donald Trump's most loyal aides, is resigning. (Feb. 28)
AP

The announcement came the day after Hicks declined to answer questions from a House committee investigating whether the Trump campaign colluded with Russian agents during the 2016 presidential election. Various accounts of that testimony — in which she reportedly said she often told white lies on behalf of the president — could have undermined her credibility with the media.

A Feb. 1 story in a British tabloid linked Hicks romantically with Rob Porter — the White House staff secretary who resigned amid reports his security clearance was held up over allegations of domestic violence.

Sanders said the departure had been in the works for a while and was unrelated to her congressional appearance. "It’s not like it happened overnight,” Sanders said. “Don’t try to make this a scandal; it’s not.”

"Hope is outstanding and has done great work for the last three years," Trump said in a written statement. "She is as smart and thoughtful as they come, a truly great person. I will miss having her by my side, but when she approached me about pursuing other opportunities, I totally understood. I am sure we will work together again in the future."

White House Chief of Staff John Kelly called Hicks "strategic, poised and wise beyond her years."

"To say that she will be missed is an understatement," Kelly said.

Hicks released a statement saying, "There are no words to adequately express my gratitude to President Trump."

Hope Hicks attends a session hosted by President Trump with student survivors of school shootings, their parents and teachers in the State Dining Room at the White House on Feb. 21, 2018 in Washington. CHIP SOMODEVILLA, GETTY IMAGES

Hicks, chief strategist Steve Bannon, then-chief of staff Reince Priebus and policy adviser Stephen Miller walk across the South Lawn of the White House to join President Trump aboard Marine One as he departs the White House en route to Harrisburg, Pa., on April 29, 2017. Ron Sachs, Pool

Hicks and Liberty University President Jerry Falwell Jr., left, listen to Trump during a campaign rally at the Loudoun County Fairgrounds on Nov. 6, 2016, in Leesburg, Va. Chip Somodevilla, Getty Images